100% true, but oxygen is more "electronegative", which means that it hoards it's electrons more closely to it's nucleus. It's the fact that the electron shells around an oxygen nucleus are smaller that make oxygen a smaller atom than nitrogen and O2 a smaller molecule than N2.

Except for Fluorine at 4.0, Oxygen is the most highly electronegative atom on the periodic table at 3.5

Bond Polarity

You gotta know this stuff to be king.